Toxic waste spill threatens Spanish national park

MADRID (Reuters) - Spain's biggest nature reserve was in danger of contamination on Saturday after a Canadian-owned mining company's toxic waste spilled into a major river, officials said.

One environmental group called the incident "a catastrophe of the highest order."

Environment Minister Isabel Tocino toured the scene by helicopter after the waste reservoir at the Los Frailes mine ruptured, sending up to five million cubic meters of contaminated water rushing into the Guadiamar River near the southern city of Seville.

Authorities scrambled to build a makeshift retaining wall around the Donana National Park to prevent the toxic water from entering the reserve.

The regional chapter of the farmers' association Asaja said up to 10,000 hectares (25,000 acres) of farmland may have been affected by the spill.

The mayors of seven towns along the river warned citizens not to drink from wells. Sheep and cattle owners were told to keep livestock away from the river. Fishing is also expected to be affected.

No casualties were reported.

The Guadiamar River flows through Donana

The water in the reservoir was contaminated with traces of heavy metals, mineral sediment and acidic chemicals, officials said.

Public health investigators were analyzing the river water to determine the extent of the contamination.

As seen from the air, the dark stain of the spill is about one kilometer long and traveling at about one kilometer an hour. At that pace, the contaminated water will reach the park during the early hours of Sunday.

The long containing wall being thrown up at the national park is designed to block off the entire flow of the Guadiamar, rerouting the water through a man-made canal and on into the Guadalquivir.

The normal course of the Guadiamar, which rises in mountains some 100 kilometers north of Seville, takes it through the park before it joins the Guadalquivir.

A 'catastrophe' for Spain

The major risk to the plan is that the tide could keep the contaminated waters from reaching the Guadalquivir.

In Toronto, the Canadian owners of the mine -- Boliden Ltd -- said a tailings-dam dike had breached, sending water and pyrite-containing solids into the river.

The breach occurred late on Friday as the dike failed along a 164-foot (50-meter) section. Initial inspections indicated the ground beneath the dike slipped, Boliden said in a statement.

The environmental group Greenpeace asked the Spanish Attorney General's office to open an investigation into who was responsible for the spill, saying: "This is clearly a case of environmental crime."

Greenpeace called for urgent efforts to control the toxic flow and measures to avoid damage to underground water supplies.

The Environmental Association for the Defense of Nature warned that Spain was "facing a catastrophe of the highest order."

"This is a new threat to one of the most important environmental treasures that currently exists," the group said in a statement.

The Guadiamar is the principal source of fresh water for the Donana park, which is made up of vast stretches of dunes, forests and marshes. The park is home to more than 250 bird species.